This invention relates generally to a document image assessment system and method and more particularly to a system and method for evaluating one or more attributes of a document image to provide an indication of the condition of the document image.
High speed imaging devices have been developed to help automate the processing of large volumes of documents. One such device is used by the Internal Revenue Service to process tax return papers. Typically, these devices include a scanner, a document feeder, and a document transport mechanism which has a known uniform background. Documents are loaded into the document feeder which feeds each document on to the document transport mechanism. The scanner captures a document image of each document against the background of the document transport mechanism in a frame of information. The frame of information is then stored for further processing.
Although high speed imaging devices increase the number of documents which can be processed, these devices have limitations. In particular, high speed imaging devices can not provide an indication of the condition of the document image captured in the frame of information. If an indication of the condition of the document image was provided then a determination on whether the document image is suitable for further processing could be made. Examples of some conditions which might be monitored included checks for tears in the document, for corners which were folded over when the document was scanned, multiple documents which were accidentally scanned together covering at least a portion of one of the documents, sheet and line skew, and average character confidence over the entire document. Human operators could be used to evaluate the condition of each document image, but this would substantially reduce the throughput of the high speed imaging devices, thus defeating their usefulness.
A need has therefore been felt for a system and method for automatically evaluating the condition of one or more document images. Additionally, a need has been felt for a system and method which can automatically evaluate the geometrical integrity of a document image, the condition of the text in a document image, and the condition of the text with respect to a predetermined frame of reference. Further, a need has been felt for a system and method which can assess document images utilizing the information obtained from the original scan of the documents.
A system and method in accordance with the present invention includes a scanning assembly and a storage device coupled to a programmed computer. The programmed computer has a set of instructions for carrying out the assessment of document images. The system and method operate by: processing the document image to obtain one or more attributes related to the geometrical integrity of the document image; selecting a threshold value from a database for each of the obtained attributes; and then comparing each of the obtained attributes against the threshold value selected for the obtained attribute to determine a difference for each and then evaluating one or more of the differences using predetermined criteria to provide evaluation results of the geometrical integrity of the document image. The system and method may also operate to: process the document image to obtain attributes related to line skew, average character confidence, expected contrast, and sharpness in the document image; select a threshold value from a database for each of the obtained attributes; and compare each of the obtained attributes against the threshold value selected for the obtained attribute to determine the difference for each and then evaluate one or more of the differences using predetermined criteria to provide evaluation results of the condition of the text of the document image and of the condition of the image with respect to a fixed reference.
With the document image assessment system and method, document images which are not suitable for further processing can be identified. For example, if a document which was scanned into a frame of information was torn or had one or more corners folded over, document image assessment system and method would be able to provide evaluation results which would identify these problems and provide information on the extent of the problems or could simply provide an error signal. The system and method are dynamic, allowing an operator to adjust what attributes from each document image are obtained, what threshold values are used, and what criteria is used for each assessment. With the system and method, the throughput of the high speed imaging devices can be maintained because evaluations of each document image by a human operator are unnecessary. Additionally, the system and method do not necessitate any additional information beyond that obtained from the original scan of the document.